Synopsis This book deals with the block diagram level of Computer System Architecture. Experience shows that not a sufficient amount of real constraints and real design information accompanies the information that many people learn about computer design and computer architecture. Though the design of the components of the system –the adders, the multipliers, the interface elements, and other hardware items – is understood to some degree at the conceptual level, but often people are unable to match devices to the functions. This text is certainly about the real examples and real systems. In an attempt to identify the concepts and put real devices and methods with them, some examples are selected from a variety of real machines. Examples of instruction are selected from different processors to illustrate different methods of performing some operation.